Method for recovering nickel from sulfuric acid aqueous solution

Abstract

A method for recovering nickel from sulfuric acid aqueous solution, for recovering nickel in an effectively utilizable form as a raw material of nickel industry material, by separating efficiently impurity elements of iron, aluminum, manganese, etc., from the sulfuric acid aqueous solution containing nickel and cobalt, and the impurity elements, iron, aluminum, manganese, etc. The method comprises the following steps: subject the sulfuric acid aqueous solution to oxidation neutralization treatment; then subject the solution to neutralization treatment, and separate and recover mixed hydroxides containing nickel and cobalt; subject the mixed hydroxides to dissolution treatment in a sulfuric acid solution having a concentration of equal to or higher than 50% by mass; subject the concentrated solution to solvent extraction treatment, using a phosphate ester-based acidic extraction agent; add a neutralizing agent to the resultant extraction residual liquid; subject the solution to the neutralization treatment, and separate and recover nickel hydroxide generated.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a method for recovering nickel from an sulfuric acid aqueous solution, and more specifically the present invention relates to a recovering method for nickel from the sulfuric acid aqueous solution, which is capable of enhancing economical efficiency as a smelting process, as well as recovering nickel in an effectively utilizable form as a raw material of nickel industry material such as metallic nickel, nickel oxide, ferronickel, and at the same time, separating cobalt, which is an expensive valuable metal, as a byproduct easy to utilize, by removing efficiently impurity elements of iron, aluminum, manganese and the like, from the sulfuric acid aqueous solution containing nickel and cobalt, and the impurity elements of iron, aluminum, manganese and the like. In this way, the present invention is suitably used as a method for separating and recovering nickel and cobalt from a leach soluti...

AI Technical Summary

Benefits of technology

[0021]In view of the above conventional technical problems, it is an object of the present invention to provide a method for recovering nickel from the sulfuric acid aqueous solution, which is capable of enhancing economical efficiency as a smelting process, as well as recovering nickel in an effectively utilizable form as a raw material of nickel industry material such as metallic nickel, nickel oxide, ferronickel, and at the same time, separating cobalt, which is an expensive valuable metal, as a byproduct easy to utilize, by removing efficiently impurity elements of iron, aluminum, manganese and the like, from the sulfuric acid aqueous solution containing nickel and cobalt, and the impurity elements of iron, aluminum, manganese and the like.Means for Solving the Problem

[0022]The present inventors have intensively studied a method for recovering nickel from the sulfuric acid aqueous solution containing nickel and impurity elements of cobalt, iron, aluminum, manganese and the like, to attain the aforesaid objects, and found that by performing sequentially, the step to subject the sulfuric acid aqueous solution to oxidation neutralization treatment under specific condition, and to remove iron and aluminum; the step to subject the resultant solution after the oxidation neutralization treatment to neutralization treatment under specific condition, and to separate and recover mixed hydroxides containing nickel and cobalt; the step to subject the resultant mixed hydroxides to dissolution treatment under specific condition, and to obtain a concentrated solution of nickel and cobalt, while removing manganese; the step to subject the resultant concentrated solution to oxidation treatment under specific condition, and to remove manganese; the step to subject the resultant solution after the oxidation treatment to solvent extraction treatment under specific condition, to obtain an extraction residual liquid containing nickel and an back extraction liquid containing cobalt; and the step to subject the resultant extraction residual liquid to the neutralization treatment, nickel hydroxide which can be effectively utilized as a raw material of industrial material can be recovered in high yield, as well as cobalt can be recovered also in an easy to utilize state, and have thus completed the present invention.

[0054]The method for recovering nickel of the present invention from the sulfuric acid aqueous solution is capable of recovering nickel hydroxide with nickel content concentrated to equal to or higher than 40% by mass, which can be effectively utilized as a raw material of nickel industry material such as metallic nickel, nickel oxide, ferronickel, by removing efficiently impurity elements of iron, aluminum, manganese and the like, from the sulfuric acid aqueous solution containing nickel and cobalt, and the impurity elements of iron, aluminum, manganese and the like. In addition, it is capable of separating cobalt, which is an expensive valuable metal, as a usable byproduct. As understood from the above, industrial value thereof is extremely high.

Problems solved by technology

In such a hydrometallurgical process, a leach solution to be produced is the sulfuric acid aqueous solution containing nickel, along with various kinds of impurity elements such as, beginning fromcobalt, iron, aluminum, manganese, zinc, chromium, magnesium, silicon, contained in an ore, and it was an important problem in view of a smelting process, to separate and recover nickel, and cobalt, if necessary, by an efficient means.

However, in the hydrometallurgical process (A), because it is one not to separate nickel and cobalt, and recover them as mixed sulfides, although the resultant mixed sulfides are suitable as raw materials of a smelting process provided with the steps to leach them, then separate nickel and cobalt to recover each of them as a highly pure product, for example, a chlorine leach method, but on the other hand, it had a problem not able to be used directly, as raw materials for production of, for example, ferronickel or stainless steel production, in a process having limitation in view of load of cobalt, sulfur or the like in supplied raw materials.

In addition, in the hydrometallurgical process (B), although the resultant nickel hydroxide can be used as a raw material of ferronickel production, because cobalt has been separated and sulfur has been removed, but on the other hand, there was a problem, as a problem in view of a smelting process, that nickel concentration of a neutralization solution, as a starting solution of the solvent extraction step, is several g / L, the same level as that of a leach solution, because the special step is not installed for increasing nickel concentration of the leach solution and the neutralization solution, and thus in a solvent extraction treatment using such a low concentration solution, use amount of the extraction agent and equipment scale become too large, which is not economically efficient due to loss of the extraction agent and equipment cost.

In addition, in the hydrometallurgical process (C), although the resultant nickel hydroxide, in which cobalt is separated, and thus can be utilized effectively as a raw material of metallic nickel, nickel oxide, ferronickel or the like, but on the other hand, there was an economical problem in a leach method itself, because the RIP (Resin In Pulp) method is adopted in the leaching step, as a smelting process, because of wear or the like of an expensive ion-exchange resin in slurry, use amount and loss thereof becomes excessive, as well as nickel concentration of an acidic eluent, as a starting solution of the solvent extraction step, is 10 to 80 g / L at most, although concentration effect is expected by use of the ion-exchange resin, and thus in a solvent extraction treatment using such a low concentration solution, use amount of the extraction agent and equipment scale become excessive, similarly as in the hydrometallurgical process (B).

In addition, in the hydrometallurgical processes (B) and (C), because the special step is not installed for removing manganese from the starting solution of the solvent extraction step, in adopting a phosphate ester-type acidic extraction agent as the extraction agent to extract cobalt from the starting solution to an organic phase, extraction efficiency of cobalt deteriorates influenced by manganese extracted together, therefore, there were also problems of increase in use amount of the extraction agent and increase in manganese concentration in the back extraction liquid containing cobalt.

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